Malignant melanoma is an immunogenic, highly aggressive and often lethal form of skin cancer. It is the most common cancer in the 17-34 years age group but affects people of all ages, and therefore has a significant socioeconomic impact for patients and their families. Although diagnosed skin lesions can be initially excised by surgical intervention, skin and distal metastases unfortunately occur in 20% of patients originally treated with local disease. Patients with lymph node and other distal metastases have dismal prognosis, and this is partly due to lack of effective treatments for this cohort.
Melanoma has presented major challenges to numerous targeted therapy efforts and therefore effective treatments are urgently needed for patients with this disease. The recent approval of the monoclonal antibody ipilimumab (targeting the CTLA4 blockade to enhance T cell activation) for the treatment of melanoma lends merit to the notion that activating immune responses with antibodies may have therapeutic significance and has renewed interest in the field of antibody therapies for the treatment of challenging tumours such as melanoma.
Interferons have been contemplated for use in the treatment of cancer (Borden et al. (2005) J. Interferon Cytokine Res. 25: 511-527; Borden et al. (2007) Nat. Rev. Drug Discov. 6: 975-690). There are seven classes of type I IFNs with IFNα and IFNβ being the most abundant. Both IFNα and IFNβ bind to the same receptor composed of two transmembrane proteins, IFNAR 1 and 2, but IFNβ binds with much higher affinity than IFNα (Lamken et al. (2004) J. Mol. Biol. 341: 303-318). IFNs have been shown to have anti-proliferative activity as well as the ability to induce apoptosis in hematological malignancies and solid tumors in addition to their anti-viral activity (as reviewed in Borden et al. (2007) Nat. Rev. Drug Discov. 6: 975-690). However, the effectiveness of IFNα for cancer therapy is overshadowed by side effects when used at high doses (Weiss (1998) Semin. Oncol. 25: 9-13) and by a short half-life, e.g., of only 1 hour (Peleg-Shulman et al. (2004) J. Med. Chem. 47: 4897-4904). Strategies to increase the half-life have included the covalent linkage of polyethylene glycols (PEG) to IFNα (Talpaz et al. (2001) Blood, 98: 1708-1713), but such modifications have resulted in lower activity (Rosendahl et al. (2005) Bioconjug. Chem. 16: 200-207).